glorious path to the discouraged poet. M. de Moncaville offered to teach
him mathematics, in exchange for drawing-lessons that his son received
from the warder of the king's pictures. The proposal being accepted, the
progress of Sylvain Bailly in these studies was rapid and brilliant.
BAILLY BECOMES THE PUPIL OF LACAILLE.--HE IS ASSOCIATED WITH HIM IN HIS
ASTRONOMICAL LABOURS.
The mathematical student soon after had one of those providential
meetings which decide a young man's future fate. Mademoiselle Lejeuneux
cultivated painting. It was at the house of this female artist, known
afterwards as Madame La Chenaye, that Lacaille saw Bailly. The
attentive, serious, and modest demeanour of the student charmed the
great astronomer. He showed it in a most unequivocal manner, by
offering, though so avaricious of his time, to become the guide of the
future observer, and also to put him in communication with Clairaut.
It is said that from his first intercourse with Lacaille, Bailly showed
a decided vocation for astronomy. This fact appears to me incontestable.
At his first appearance in this line, I find him associated in the most
laborious, difficult, and tiresome investigations of that great
observer.
These epithets may perhaps appear extraordinary; but they will be so
only to those who have learnt the science of the stars in ancient poems,
either in verse or in prose.
The Chaldæans, luxuriously reclining on the perfumed terraced roofs of
their houses in Babylon, under a constantly azure sky, followed with
their eyes the general and majestic movements of the starry sphere; they
ascertained the respective displacements of the planets, the moon, the
sun; they noted the date and hour of eclipses; they sought out whether
simple periods would not enable them to foretell these magnificent
phenomena a long time beforehand. Thus the Chaldæans created, if I may
be allowed the expression, _Contemplative Astronomy_. Their observations
were neither numerous nor exact; they both made and discussed them
without labour and without trouble.
Such is not, by a great deal, the position of modern astronomers.
Science has felt the necessity of the celestial motions being studied in
their minutest details. Theories must explain these details; it is their
touchstone; it is by details that theories become confirmed or fall to
the ground. Besides, in Astronomy, the most important truths, the most
astonishing results, are based on the measurement of quantities of
extreme minuteness. Such measures, the present bases of the science,
require very fatiguing attention, infinite care, to which no learned man
would bind himself, were he not sustained, and encouraged by the hope of
attaining some capital determination, through an ardent and decided
devotion to the subject.
The modern astronomer, really worthy of the name, must renounce the
distractions of society, and even the refreshment of uninterrupted
sleep. In our climates during the inclement season, the sky is almost
constantly overspread by a thick curtain of clouds. Under pain of
postponing by some centuries the verification of this or that theoretic
point, we must watch the least clearing off, and avail ourselves of it
without delay.
A favourable wind arises and dissipates the vapours in the very
direction where some important phenomenon will manifest itself, and is
to last only a few seconds. The astronomer, exposed to all the
transitions of weather, (it is one of the conditions of accuracy,) the
body painfully bent, directs the telescope of a great graduated circle
in haste upon the star that he impatiently awaits. His lines for
measuring are a spider's threads. If in looking he makes a mistake of
half the thickness of one of these threads, the observation is good for
nothing; judge what his uneasiness must be; at the critical moment, a
puff of wind occasioning a vibration in the artificial light adapted to
his telescope, the threads become almost invisible; the star itself,
whose rays reach the eye through atmospheric strata of various density,
temperature, and refrangibility, will appear to oscillate so much as to
render the true position of it almost unassignable; at the very moment
when extremely good definition of the object becomes indispensable to
insure correctness of measures, all becomes confused, either because the
eye-piece gets steamed with vapour, or that the vicinity of the very
cold metal occasions an abundant secretion of tears in the eye applied
to the telescope; the poor observer is then exposed to the alternative
of abandoning to some other more fortunate person than himself, the
ascertaining a phenomenon that will not recur during his lifetime, or
introducing into the science results of problematical correctness.
Finally, to complete the observation, he must read off the microscopical
divisions of the graduated circle, and for what opticians call _indolent
vision_ (the only sort that the ancients ever required) must substitute
_strained vision_, which in a few years brings on blindness.[6]
When he has scarcely escaped from this physical and moral torture, and
the astronomer wishes to know what degree of utility is deducible from
his labours, he is obliged to plunge into numerical calculations of
repelling length and intricacy. Some observations that have been made in
less than a minute, require a whole day's work in order to be compared
with the tables.
Such was the view that Lacaille, without any softening, exhibited to his
young friend; such was the profession into which the adolescent poet
plunged with great ardour, and without having been at all prepared for
the transition.
A useful calculation constituted the first claim of our tyro to the
attention of the learned world.
The year 1759 had been marked by one of those great events, the memory
of which is religiously preserved in scientific history. A comet, that
of 1682, had returned at the epoch foretold by Clairaut, and very nearly
in the region that mathematical analysis had indicated to him. This
reappearance raised comets out of the category of sublunary meteors; it
gave them definitely closed curves as orbits, instead of parabolas, or
even mere straight lines; attraction confined them within its immense
domain; in short, these bodies ceased for ever to be liable to
superstition regarding them as prognostics.
The stringency, the importance of these results, would naturally
increase in proportion as the resemblance between the announced orbit
and the real orbit became more evident.
This was the motive that determined so many astronomers to calculate the
orbit of the comet minutely, from the observations made in 1759,
throughout Europe. Bailly was one of those zealous calculators. In the
present day, such a labour would scarcely deserve special mention; but
we must remark that the methods at the close of the eighteenth century
were far from being so perfect as those that are now in use, and that
they greatly depended on the personal ability of the individual who
undertook them.
Bailly resided in the Louvre. Being determined to make the theory and
practice of astronomy advance together, he had an observatory
established from the year 1760, at one of the windows in the upper story
of the south gallery. Perhaps I may occasion surprise by giving the
pompous name of _Observatory_ to the space occupied by a window, and the
small number of instruments that it could contain. I admit this feeling,
provided it be extended to the Royal Observatory of the epoch, to the
old imposing and severe mass of stone that attracts the attention of the
promenaders in the great walk of the Luxembourg. There also, the
astronomers were obliged to stand in the hollow of the windows; there
also they said, like Bailly: I cannot verify my quadrants either by the
horizon or by the zenith, for I can neither see the horizon nor the
zenith. This ought to be known, even if it should disturb the wild
reveries of two or three writers, who have no scientific authority:
France did not possess an observatory worthy of her, nor worthy of the
science, and capable of rivalling the other observatories of Europe,
until within these ten or twelve years.
The earliest observations made by Bailly, from one of the windows in the
upper story of the Louvre gallery that looks out on the Pont des Arts,
are dated in the beginning of 1760. The pupil of Lacaille was not yet
twenty-four years old. Those observations relate to an opposition of the
planet Mars. In the same year he determined the oppositions of Jupiter
and of Saturn, and compared the results of his own determinations with
the tables.
The subsequent year I see him associated with Lacaille in observing the
transit of Venus over the sun's disk. It was an extraordinary piece of
good fortune, Gentlemen, at the very commencement of his scientific
life, to witness in succession two of the most interesting astronomical
events: the first predicted and well established return of a comet; and
one of those partial eclipses of the sun by Venus, that do not recur
till after the lapse of a hundred and ten years, and from which science
has deduced the indirect but exact method, without which we should still
be ignorant of the fact that the sun's mean distance from our earth is
thirty-eight millions of leagues.
I shall have completed the enumeration of Bailly's astronomical labours
performed before he became an academician, when I have added, from
observations of the comet of 1762, the calculation of its parabolic
orbit; the discussion of forty-two observations of the moon by La Hire,
a detailed labour destined to serve as a starting point for any person
occupying himself with the lunar theory; finally, also the reduction of
515 zodiacal stars, observed by Lacaille in 1760 and 1761.
FOOTNOTE:
[6] This long list of supposed difficulties in making an exact
observation is hardly worthy of a zealous astronomer. Our author shows
no enthusiasm for his subject here, and ends by ascribing the whole
jeremiad to Lacaille, a man of very great practical perseverance. It is
to be regretted that Arago never refers to observations of his own, but
constantly quotes from others, nor does he always select the best.
--_Translator's Note_.
BAILLY A MEMBER OF THE ACADEMY OF SCIENCES.--HIS RESEARCHES ON JUPITER'S
SATELLITES.
Bailly was named member of the Academy of Sciences the 29th January,
1763. From that moment his astronomical zeal no longer knew any bounds.
The laborious life of our fellow-academician might, on occasion, be set
up against a line, more fanciful than true, by which an ill-natured poet
stigmatized academical honours. Certainly no one would say of Bailly,
that after his election,
"Il s'endormit et ne fit qu'un somme."
"He fell asleep and made but one nap (or sum)."
On the contrary, we cannot but be surprised at the multitude of literary
and scientific labours that he accomplished in a few years.
Bailly's earliest researches on Jupiter's satellites began in 1763.
The subject was happily chosen. Studying it in all its generalities, he
showed himself both an indefatigable computer, a clear-sighted geometer,
and an industrious and able observer. Bailly's researches on the
satellites of Jupiter, will always be his first and chief claim to
scientific glory. Before him, the Maraldis, the Bradleys, the Wargentins
had discovered empirically some of the principal perturbations that
those bodies undergo, in their revolving motions around the powerful
planet that rules them; but they had not been traced up to the
principles of universal attraction. The initiative honour in this
respect belongs to Bailly. Nor is this honour decreased by the ulterior
and considerable improvements that the science has since received; even
the discoveries of Lagrange and of Laplace have left this honour intact.
The knowledge of the satellitic motions rests almost entirely on the
observation of the precise moment when each of those bodies disappears,
by entering into the conical shadow, which the immense opaque globe of
Jupiter projects on the opposite side from the sun. In the course of
discussing a multitude of these eclipses, Bailly was not long in
perceiving that the computers of the Satellitic Tables worked on
numerical data that were not at all comparable with each other. This
seemed of little consequence previous to the birth of the theory; but,
after the analytical discovery of the perturbations, it became desirable
to estimate the possible errors of observation, and to suggest means for
remedying them. This was the object of the very considerable work that
Bailly presented to the Academy in 1771.
In this beautiful memoir, the illustrious astronomer developes the
series of experiments, by the aid of which each observation may give the
instant of the real disappearance of a satellite, distinguished from the
instant of the apparent disappearance, whatever be the power of the
telescope used, whatever be the altitude of the eclipsed body above the
horizon, and consequently, whatever be the transparency of the
atmospheric strata through which the phenomenon is observed, also
whatever be the distance from that body to the sun, or to the planet;
finally, whatever be the sensibility of the observer's sight, all which
circumstances considerably influence the time of apparent disappearance.
The same series of ingenious and delicate observations led the author,
very curiously, to the determination of the true diameters of the
satellites, that is to say, of small luminous points, which, with the
telescopes then in use, showed no perceptible diameter.
I will rest contented with these general considerations; only remarking,
in addition, that the diaphragms used by Bailly were not intended only
to diminish the quantity of light contributing to the formation of the
images, but that they considerably increase the diameter, and in a
variable way, at least in the instance of stars.
Under this new aspect, it will be requisite to submit the question to a
new examination.
Any geometers and astronomers who wish to know all the extent of
Bailly's labours, must not content themselves with consulting the
collections in the Academy of Sciences; for he published, at the
beginning of 1766, a separate work under the modest title of _Essay on
the Theory of Jupiter's Satellites_.
The author commences with the _Astronomical History of the Satellites_.
This history contains an almost complete analysis of the discoveries by
Maraldi, by Bradley, by Wargentin. The labours of Galileo and his
contemporaries are given with less detail and exactness. I have thought
that I ought to fill up the lacunæ, by availing myself of some very
precious documents published a few years since, and which were unknown
to Bailly.
But this I will do in a separate notice, free from all preconceived
ideas, and free from all party spirit; I will not forget that an honest
man ought not to calumniate any one, not even the agents of the
Inquisition.
BAILLY'S LITERARY WORKS.--HIS BIOGRAPHIES OF CHARLES V.--OF
LEIBNITZ--OF PETER CORNEILLE--OF MOLIÈRE.
When Bailly entered the Academy of Sciences, the perpetual secretary was
Grandjean de Fouchy. The bad health of this estimable scholar occasioned
an early vacancy to be foreseen. D'Alembert cast his views on Bailly,
hinted to him the survivorship to Fouchy, and proposed to him, by way of
preparing the way, to write some biographies. Bailly followed the advice
of the illustrious geometer, and chose as the subject of his studies,
the éloges proposed by several academies, though principally by the
French Academy.
From the year 1671 to the year 1758, the prize subjects proposed by the
French Academy related to questions of religion and morality. The
eloquence of the candidates had therefore had to exercise itself
successively on the knowledge of salvation; on the merit and dignity of
martyrdom; on the purity of the soul and of the body; on the danger
there is in certain paths that appear safe, &c. &c. It had even to
paraphrase the _Ave Maria_. According to the literal intentions of the
founder, (Balzac,) each discourse was ended by a short prayer. Duclos
thought in 1758, that five or six volumes of similar sermons must have
exhausted the matter, and on his proposal the Academy decided that, in
future, it would give as the subject of the eloquence prize, the
eulogiums of the great men of the nation. Marshal Saxe, Duguay Trouin,
Sully, D'Aguesseau, Descartes, figured first on this list. Later, the
Academy felt itself authorized to propose the éloge of kings themselves;
it entered on this new branch at the beginning of 1767, by asking for
the éloge of Charles V.
Bailly entered the lists, but his essay obtained only an honourable
mention.
Nothing is more instructive than to search out at what epoch originated
the principles and opinions of persons who have acted an important part
on the political scene, and how those opinions developed themselves. By
a fatality much to be regretted, the elements of these investigations
are rarely numerous or faithful. We shall not have to express these
regrets relative to Bailly. Each composition shows us the serene,
candid, and virtuous mind of the illustrious writer, in a new and true
point of view. The éloge of Charles V. was the starting point, followed
by a long series of works, and it ought to arrest our attention for a
while.
The writings, crowned with the approbation of the French Academy, did
not reach the public eye till they had been submitted to the severe
censure of four Doctors in Theology. A special and digested approbation
by the high dignitaries of the Church, whom the illustrious assembly
always possessed among her members, was not a sufficient substitute for
the humbling formality. If we are sure that we possess the éloge of
Charles V. such as it flowed from the author's pen; if we have not
reason to fear that the thoughts have undergone some mutilation, we owe
it to the little favour that the discourse of Bailly enjoyed in the
sitting of the Academy in 1767. Those thoughts, however, would have
defied the most squeamish mind, the most shadowy susceptibility. The
panegyrist unrolls with emotion the frightful misfortunes that assailed
France during the reign of King John. The temerity, the improvidence of
that monarch; the disgraceful passions of the King of Navarre; his
treacheries; the barbarous avidity of the nobility; the seditious
disposition of the people; the sanguinary depredations of the great
companies; the ever recurring insolence of England; all this is
expressed without disguise, yet with extreme moderation. No trait
reveals, no fact even foreshadows in the author, the future President of
a reforming National Assembly, still less the Mayor of Paris, during a
revolutionary effervescence. The author may make Charles V. say that he
will discard favour, and will call in renown to select his
representatives; it will appear to him that taxes ought to be laid on
riches and spared on poverty; he may even exclaim that oppression
awakens ideas of equality. His temerity will not overleap this boundary.
Bossuet, Massillon, Bourdaloue, made the Chair resound with bold words
of another description.
I am far from blaming this scrupulous reserve; when moderation is united
to firmness, it becomes power. In a word, however, Bailly's patriotism
might, I was about to say ought to, have shown itself more susceptible,
more ardent, prouder. When in the elegant prosopopoeia which closes
the éloge, the King of England has recalled with arrogance the fatal day
of Poitiers, ought he not instantly to have restrained that pride within
just limits? ought he not to have cast a hasty glance on the components
of the Black Prince's army? to examine whether a body of troops,
starting from Bordeaux, recruiting in Guienne, did not contain more
Gascons than English? whether France, now bounded by its natural limits,
in its magnificent unity, would not have a right, every thing being
examined, to consider that battle almost as an event of civil war? ought
he not, in short, to have pointed out, in order to corroborate his
remarks, that the knight to whom King John surrendered himself, Denys de
Morbecque, was a French officer banished from Artois?
Self-reliance on the field of battle is the first requisite for
obtaining success; now, would not our self-reliance be shaken, if the
men most likely to know the facts, and to appreciate them wisely,
appeared to think that the Frank race were nationally inferior to other
races who had peopled this or that region, either neighbouring or
distant? This, let it be well remarked, is not a puerile susceptibility.
Great events may, on a given day, depend on the opinion that the nation
has formed of itself. Our neighbours on the other side of the Channel,
afford examples on this subject that it would be well to imitate.
In 1767, the Academy of Berlin proposed a prize for an éloge of
Leibnitz. The public was somewhat surprised at it. It was generally
supposed that Leibnitz had been admirably praised by Fontenelle, and
that the subject was exhausted. But from the moment that Bailly's essay,
crowned in Prussia, was published, former impressions were quite
changed. Every one was anxiously asserting that Bailly's appreciation of
his subject might be read with pleasure and benefit, even after
Fontenelle's. The éloge composed by the historian of Astronomy will not,
certainly, make us forget that written by the first Secretary of the
Academy of Sciences. The style is, perhaps, too stiff; perhaps it is
also rather declamatory; but the biography, and the analysis of his
works, are more complete, especially if we consider the notes; the
_universal_ Leibnitz is exhibited under more varied points of view.
In 1768, Bailly obtained the award of the prize of eloquence proposed
by the Academy of Rouen. The subject was the éloge of Peter Corneille.
In reading this work of our fellow-academician, we may be somewhat
surprised at the immense distance that the modest, the timid, the
sensitive Bailly puts between the great Corneille, his special
favourite, and Racine.
When the French Academy, in 1768, proposed an éloge of Molière for
competition, our candidate was vanquished only by Chamfort. And yet, if
people had not since that time treated of the author of "Tartufe" to
satiety, perhaps I would venture to maintain, notwithstanding some
inferiority of style, that Bailly's discourse offered a neater, truer,
and more philosophic appreciation of the principal pieces of that
immortal poet.
DEBATES RELATIVE TO THE POST OF PERPETUAL SECRETARY OF THE ACADEMY OF
SCIENCES.
We have seen D'Alembert, ever since the year 1763, encouraging Bailly to
exercise himself in a style of literary composition then much liked, the
style of éloge, and holding out to him in prospect the situation of
Perpetual Secretary of the Academy of Sciences. Six years after, the
illustrious geometer gave the same advice, and perhaps held out the same
hopes, to the young Marquis de Condorcet. This candidate, docile to the
voice of his protector, rapidly composed and published the éloges of the
early founders of the Academy, of Huyghens, of Mariotte, of Roëmer, &c.
At the beginning of 1773, the Perpetual Secretary, Grandjean de Fouchy,
requested that Condorcet should be nominated his successor, provided he
survived him. D'Alembert strongly supported this candidateship. Buffon
supported Bailly with equal energy; the Academy presented for some
weeks the aspect of two hostile camps. There was at last a strongly
disputed electoral battle; the result was the nomination of Condorcet.
I should regret if we had to judge of the sentiments of Bailly, after
this defeat, by those of his adherents. Their anger found vent in terms
of unpardonable asperity. They said that D'Alembert had "basely betrayed
friendship, honour, and the first principles of probity."